Telephone system.



No. 746,040. PATENTED DEC. 8, 1903. W. W. DEAN.

TELEPHONE SYSTEM.

APPLICATION FILED MAY 27, 1901. H0 MODEL.

Patented December 8, 1903.

UNITED STATES PATENT OFFICE.

IVILLIAM NV. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCH- BOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent N 0. 746,040, dated December 90 Application filed May 27, 1901. Serial lilo. 62,031- (No model.)

To (tZZ ZU7'l/O7'Fl/ it irtrty concern:

Beit known thatLWILLIAM \V. DEAN,a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented new and useful Improvements in Telephone Systems, of which the following is a specification.

My invention relates to telephone systems wherein subscribers lines terminate at a central ofiice having means to interconnect the several lines for conversational purposes. It has special reference to those systems employing central sources of current-su pply for the operation of all signals and in which signaling from the subscribers stations to the central office is entirely automatic. Such lines commonly employ a central battery and an electromagnetic signaling device in the circuit which is adapted to be operated when the subscriber closes his line-circuit by taking up his receiver. A cut-off relay is also ordinarily provided for each line to render the said line-signal inoperative when a connection is established with the line, so that it will not be exposed during the connection. Cord or link circuits having supervisory signals associated therewith are also provided, together with means for ringing a subscriber and for inserting the operators telephone in the lines.

Systems have been devised employing cutoff relays that. are insensitive or unresponsive to calling-current, soihatthe line-signal will be exposed when a subscriber calls, but that are sensitive or responsive to current thrown upon the line in the establishment of a conncction therewith. to render the said signal stations A and B are shown having the usual apparatus adapted for central-battery use, including a receiver 9 and a transmitter 8 in a normally open bridge of the line through the hook-switch 10, as well as a cendenser c, and a bell b in a normally closed branch between the line conductors 1 and 1 which lead to the central ofiice and are there connected with the multiple jacks J and J and are continued through the polarized cut-0E relay 7", the line-relay 'r', and the battery B, a ground connection G being also provided. The line-relay is adapted to close a local circuit through its armature and forward contact containing the line-signal S and the battery B.

At the central office C a cord-circuit D is provided and comprises the plugs P and P, having the tip and sleeve contacts 10 and p, the former being connected by the tip-strands if and 25, while the latter are similarly connected by thesleeve-strands sand 8, the condensers 0 being inserted between the two portions of each strand to inductively connect them for the free passage of voice-currents. The strands t and t are conductively connected, by means of branch conductors 2, with the grounded pole of the talking-battery B said branches including the supervisory relays T and the sleeve-strands sand 3' are connected in like manner by branch conductors 3 with the other pole of the talking-battery B and likewise include supervisory relays r These relays control the continuity of the circuits of the supervisory signals S and S which are associated, respectively, with the answering and calling plugs P and P of the cord-circuit, the relays r serving to normally open said circuits to darken the lamps and the former being adapted to close the said circuits when deuergized.

The operators set is adapted to be bridged between the strands s and if of the cord-circuit and includes the receiver 11, an induction-coil 12, and a condenser c in series in said bridge, the transmitter 13 being preferably charged from the main battery B A grounded ringingenerator 4 is adapted to be connected with the calling-plug P by the ringing-key 5 for the purpose of calling sub scribers, a branch conductor 6, parallel to the strand 8 of the cord-circuit, being provided for the free passage of the ringing-current.

The operation is substantially as follows: The subscriber at station A, for example, removes hisreceiverand closes the circuit from the battery B over the metallic line and through the cut-01f and line relays r and 7*; but as the cut-off relay r is polarized and so biased as not to be operated by the current now flowing the line-relay r only responds to close the circuit of line-lamp S. The operator upon observing the signal inserts the answering-plug Pinto a jack of the line, and thereby connects the cord-circuit battery B with the line and at the same time completes a local circuit from ground G at the cordcircuit through the talking-battery B over the branch conductor 3, the strand 8 of the cord-circuit, the sleeve-contacts of the plug and jack, through a portion of the talkingcircuit, the polarized cut-off relayr to ground at G. This, it will be observed, sends current through the cut-off relay 7 in a reverse direction from that previously flowing and causes it to cut out the line-relay r and extinguish the lamp S. To accomplish this purpose, thebattery 13 must have its opposite pole grounded from that of the battery B, which necessitates at least two sets of batteries for the exchange. The completion of the local circuit above traced also causes the energization of supervisory relay 7 which closes the circuit of supervisory lamp S butiuasmuch as the subscribers telephone is off the hook the supervisory relay r is likewise operated over the line-circuit and opens the circuit of said lamp, thereby causing the same to remain dark. Upon learning the numberof the subscriber wanted his line is tested, and if idle the calling-plug P is inserted in a jack of the line and the ringing-key 5 operated. Thepath fortheringing-current may betraced from ground G through the generator to the subscribers station and back through the parallel branch or by-path 6, the battery B to ground G. It will be understood that the lower spring of the ringing-key 5 cannot be directly grounded, for the reason that the battery B would be grounded or practically short-circuit-ed instead of passing through the polarized cut-off relay 0; also, that while the parallel branch 6 may not be necessary it serves to prevent any possible vibration of the armature of the supervisory relay r in the strand .9. Before the called subscriber responds the supervisory relay 1' and the cutoff relay 0' are operated over the local circuit, similar tot-he one before described. The linerelay 7'' is thus out out, and the supervisory lamp S is illuminated and remains so until the subscriber responds, when the supervisory relay r is operated over the metallic line to the station E to break the circuit ofsaid lamp and extinguish it. The parties are now in conversation, the battery B serving to charge their transmitters while the voicecurrents are transmitted through the condensers c from one line to the other. The relays r it will be observed, are under the control of the respective subscribers, while the relays r are energized as long as the plugs are in the line sockets or jacks.

In making the busy test it is only necessary to touch the tip of the calling-plug to the ring of the subscribers jack, which ring if the line is busy is connected to the live side of the battery and a circuit is completed through the tip of the plug to the other side of said battery and causes a click in the operators receiver.

At the termination of the conversation when the subscribers return their receivers to the books the metallic line-circuits from the battery B will be opened at the hooks, thus causing the supervisory relays 7 1.0 release their armatures and close the circuits of the supervisory lamps S and S which lamps become lighted and indicate to the operator that the conversation is terminated, when the plugs are withdrawn, relays r and r deenergized, and all parts restored to normal condition.

The several ground connections referred to may be the common office return or ground connection but, as beforestated,separate batteries B and B must be used in order to send current in reverse directions through the cutofi relays when a subscriber calls and when a connection is established with the line.

Good results have been obtained with polarized cut-off relays of five hundred ohms resistance and line-relays of one hundred ohms resistance, with the other parts of the usual or desired dimensions, though these sizes are not absolutely essential and may be varied without departing from the spirit of my in-' vention. Other signaling devices might also be employed; but those shown are deemed preferable.

What I claim is 1. In a telephone system, the combination with a telephone-line, of a source of current with which the line is connected at the central office, a line signaling device responsive to current in the line when the subscriber is calling the central office, a polarized cut'off device connected with the line and adapted when operated to render the line-signal inoperative, said cut-off device being in the path of current in the line when the subscriber is calling the central oilice, but unresponsive to such current so that the said signalingdevice is not prevented from operation, and means for reversing current through said on t-off de-. vice when a connection is established with the line for conversation to thereby operate the said cut-off device and prevent the signal from operating, substantiallyas described.

2. In a telephone system, the combination with a telephone-line, a line-signal, of a polarized electromagnetic device for the line serving when operated to render the said signal inoperative, a common central source of current with which the lines of the system are connected, a switch at the substation of the line to control the flow of current in the line from the central office, and means to reverse current through said device when a connection is established with the line, whereby in the firstinstance theline-signal may be caused to operate from the substation and in the second instance is prevented from operation, substantially as described.

3. In a telephone system, the combination with a multiple-switchboard telephone-line, of a line-signal therefor, a polarized device adapted when operated to render said signal inoperative, said device being in the path of current in the line from the central office when the subscriber is calling but unresponsive to current of that direction, a cord-circuit to establish connections for conversation, a source of current to furnish current over the telephone-line for conversation, and means for including said source and said device in a local circuit when connection is established with the. line, the current in said local circuit from said source being in the reverse direction through said device and serving to operate the same to render the said signal inoperative, substantially as described.

a. In a telephone system, the combination with a line-circuit, of a polarized cut-oft relay for said circuit unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction, a line-relay. a source of current, and means to operate the cut-off relay to cut out the linerelay.

5. In a telephone system, the combination with a line-circuit, of a polarized cut-oft relay for said circuit, a line-relay, means for sending current in one direction through said polarized relay when the subscriber calls, and further means for sending current in the other direction therethrough when a connection is established with the line.

6. In a telephone system, the combination with a line-circuit, of a polarized cut-off relay in the line-circuit, line-relay, a source of current also in said circuit so connected that the polarized relay will not be operated when a subscriber calls, another source of current, and means to connect the same to the line for talking and so as to operate the cut-off relay.

7. In a telephone system, the combination with a line-circuit, of a polarized cut-off relay in the line-circuit unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction, a line-relay, a source of current also in the line-circuit so connected that the polarized relay Will not operate when a subscriber calls, and meansfor sending current through said cut-0t? relay in a direction to operate it when a connection is established with the line.

8. In a telephone system, the combination with a line-circuit, of a polarized cutofli relay in the line-circuit, a line-relay, a source of current also in the line-circuit so connected that the polarized relay will not operate when a subscriber calls, a cord-circuit, and another battery connected with the cord-circuit to furnish current for talking and to operate said cut-otf relay when the cord-circuit is connected with the line.

9. In a telephone system, the combination with a line-circuit, of a polarized cut-0E relay for said circuit, a line-relay, and means for sending current through said cut-off relay in reverse direct ions when a subscriber calls and when a connection is established with the line.

10. In a telephone system, the combination with a line-circuit, of a polarized cut-01f relay for said circuit, a line-relay, and means for rendering the same unresponsive when a subscriber calls and responsive when a connection exists with the line to cutout the linerelay.

11. In a telephone system, the combination with a line-circuit, of a polarized cut-ofl? magnet for said circuit unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction, a line-relay and a source of current all in series in said circuit, a line-signal controlled by said line-relay, and means for operating said cut-0E magnet to render said line-signal inoperative, substantially as described.

12. The combination with a telephone-line, of a polarized cut-off relay and a line-relayin the line, a battery to furnish current for talking, and means to close said cut-off relay and battery in a local circuit when a connection is established with the line, substantially as described.

13. The combination with a telephone-line, of a central battery with which the limbs of said line are connected, a line-relay in one limb of the line, and a polarized cut-oft relay having its winding in the other limb of the line and adapted to open the first-named limb to render the line-relay inoperative, substantially as described.

l-t. The combination with a telephone-line, of a central battery, a polarized cut-olfrelay unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction and a line-relay in the ICO IIO

line, a line-signal controlled by the line-relay I l and a third conductor adapted to be con nected about the cut-elf relay and battery whereby the cut-off relay is actuated when a con- 7 nection is established with the line to render the line-signal inoperative, substantiallyas described. 15. The combination with atelephone-line, of a line-relay, a battery and a polarized cutoif relay in the line, and means to close-acircuit through the cut-off relay when a connection is established with the line, said circuit including a portion of one side of the talking-circuit, substantially as described.

16. The combination with a telephone-line, of a line-relay, a battery, a polarized cut-off relay permanently connected with the line of a line-relay, a battery, a polarized cut-0E.

magnet in the line, and means to close a cir-v cuit through the cut-off magnet when a connection is established with the line over which current flows in the proper direction to operate thecut-ofi magnet, said circuit including a portion of the telephone-line and cord-circuit, substantially as described.

18. The combination with a telephone-line, of a line-relay, a battery and a polarized cutoff device in the line, the said device being unresponsive to current flowing therethrough in one direction but responsive to currentin the opposite direction, a cord-circuit, and means to close a circuit through the cut-01f device when a connection is established with the line over which current flows in the proper direction to operate saidcut-off device, said circuit including a portion of one side of the talking-circuit of the telephone-line and cordcircuit, substantially as described.

19. The combination with a telephone-line, of a line-relay and a polarized cut-01f device in the line, a cord-circuit, and two supervisory relays connected with said circuit, one of said relays being adapted to be closed in a local circuit with the winding of said cut-olf device over which current flows in the proper direction to operate said cut-0E device,whereby one relay of the two is controlled by the operator and the other of said relays is controlled by the subscriber over the line-circuit, substantially as described.

20. In a telephone system, the combination with a subscribers line, of a signal-controlling electromagnet and a source of continuous current in the line at the central office, a polarized cut-01f relay in the line in the path of current from said source when the subscriber is calling the central office, said relay being unresponsive to said calling current, and .means to operate the relay when a connection is established with the line to render the signal-controlling electromagnet inoperative to cause a signal, substantially as described.

2i. In a telephone system, the combination with a subscribers line, of a signal-controlv ling electromagnet and a source of continuous current in the line at the central office, a polarized cut-off relay unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction having a winding connected directly in the' path of current from said source flowing in the line when the subscriber is calling the central ofiice but unresponsive thereto, and means to operate the said cut-0E relay when the connection is established with the line to render said signal-controlling electromagnet inoperative, substantially as described.

22. In a telephone system, the combination with a subscribers line having conductors normally extending to opposite poles of va source of current, of a signal-controlling electromagnet in one of said conductors, aswitch in said conductor between said magnet and the subscribers station, and a polarized cutoff relay having a winding connected in the other conductor and controlling said switch, substantially as described.

23. In a telephone system, the combination with a subscribers line normally extending to opposite poles of a source of current, of a signal-controllingelectromagnetin one of said conductors, and a polarized cut-0E relay having a winding connected in the opposite conductor and controlling the continuity of the first-named'conductor, said winding being energized over a portion of the talking-circuit when a connection is established with the line to render the signal-controlling electromagnet inoperative, substantially as described.

24. The combination withasubscribersline normally extending to opposite poles of a source of current, ofa signal-controlling electromagnet in one of said conductors, a polarized cut-off relay in the second conductor controlling the continuity of the first-named cond uctor, a cord-circuit adapted to be connected with the line in response to a call of the subscriber, and connections from said cord-circuit to a battery so as to include the same together with the winding of said cut-01f relay in a local circuit, whereby said cut-0E relay is operal ed upon the connection of the cordcircuit withthe line to render the signal-controlling electromagnet inoperative, said local circuit including a portion of the talking-circuit and said battery serving also to furnish current to the transmitter for talking purposes, substantially as described.

25. In a telephone system, the combination with a subscribers line, of a source of current connected between the limbs thereof, asignalcontrolling electromagnet in one ofsaid limbs, a polarized cutoff relay unresponsive to current flowing lherethrough in one direction but responsiveto cu rrent in the opposite direction having an actuating-winding in the other of said limbs, and normally closed switchcontacts of the said relay included in the firstnamed limb, substantially as described.

26. In a telephone system, I he combination with asubscribers line, of a source of current connected between the limbs thereof, asigualcontrollingelectromagnetin one ofsaid limbs, a polarized cut-off relay having an actuatingwinding connected in the otherot' said limb normally closed switch-contacts of said relay included in the first-named limb of the line, said relay being unresponsive to current in the line from said source when the subscriber is calling central office, and means for sending an actuating-current through said relaywinding as long as the line is switched for use to operate said relay and open its normal contacts to cut out said electromagnet, substantially as described.

27. The combination with a telephone-line, of a line-relay, a polarized cut-E relay unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction and a source of current normally in circuit with the line, the line-relay only being responsive to current from said source when the subscriber is calling, a cord-circuit adapted to be connected with the line,a supervisory signal and a battery associated therewith to furnish current for talking, and means for establishing a path for current over one side of said cord-circuit to operate said cutofi relay and supervisory signal, and a relay adapted to render said signal inoperative and having its windingdisposed in a path of current over the other side of said circuit and telephone-line, said relay being controlled by the subscriber, substantially as described.

28. The combination with a telephone-line, a line-relay, a polarized cut-off device and source of current normally in circuit with the line, the line-relay only being responsive to current from said source when the subscriber is calling, a cord-circuit adapted to be connected with the line, a source of current for talking and supervisory signal associated therewith, and means for establishing a path for current over one side of said cord-circuit to operate the cut-off device and supervisory signal, an electromagnetic device adapted to render said supervisory signal inoperative and having its winding disposed in the path of current over the other side of the cordcircuit and telephone-line, whereby said electromagnetic device is placed under the control of the subscriber, substantially as described.

29. The combination with a telephone-line, of aline-relay, a polarized cut-off magnet unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction, and a source of current normallyin circuit with theline, the line-relay only being responsive to current from said source when the subscriber is calling, a cordcircuit adapted to be connected with the line, a supervisory signal and a battery for talking associated therewith, an electromagnetic device and means for establishing a path for current over one side of said cord-circuit and through said electromagnetic device and cutoff device to operate them, said electromagnetic device serving to render the supervisory signal operative, and a second electromagnetic device having its winding disposed in the path of current over the other side of said cord-circuit and telephone-line, said second electromagnetic device being controlled by the subscriber and serving to render said supervisory signal inoperative when current is flowing in the said path, substantially as described.

30. The combination with a telephone-line, of a line-signal, a polarized cut-0H relay and source of current normally in circuit with the line, the cut-off relay being unresponsive to current from said source when the subscriber is calling, a cord-circuit adapted to be connected with the line, a supervisory signal and a battery for talking associated therewith, means for operating said signal and cut-olf relay over a local circuit when said cord-circuit is connected with the line, said local circuit includingaportion of the talking-circuit, and means controlled by the subscriber for rendering said signal inoperative by current passed over the line-circuit, said cord-circuit and battery serving also to furnish current to the transmitter for conversational purposes, substantially as described.

31. In a telephone system, the combination with a telephone-line and a polarized cut-0E relay therefor, said relay being unresponsive to current flowing'therethrough in one direction but responsive to current in the opposite direction, of a cord-circuit adapted to be connected with said line, asupervisory signal as sociated with said cord-circuit and adapted to be operated by current passed over one side of the cord-circuit when connected with the line, the actuating-winding of the cut-01f relay being included in the path of said current, whereby it is operated, and means controlled by the subscriber for rendering said signal inoperative by current passing over the linecircuit, substantially as described.

32. In a telephone system, the combination with a subscribers-telephone-line circuit normally discontinuous to direct currents at the subscribers station, of a polarized cut-ofi relay therefor at the central office, a main-line terminal for the line consisting of two normally open contact-pieces at the central office, a cord-circuit consisting of two strands and with contact-terminals adapted to connect with the contact-terminals of the line when the line is connected for conversation, a source of current associated with said cordcircuit and adapted to send current over the telephone-line to feed the subscribers transmitter, a supervisory signal associated with said cord-circuit and adapted to be operated over one side thereof when connected with the line, the circuit for operating said signal being completed over a local circuit at the central office and including the winding of said cut-off relay through which current flows in the proper direct-ion to operate the same, and means under the control of the subscriber to render said signal inoperative by closing the line-circuitat the subscribers station to form a path for currentover the linecircuit, substantially as described.

33. In a telephone system, the combination with a main line normally open or discontinuous at the subscribers station, of a telephone instrument at said subscribers station, of a calling-signal normally associated with the line at the central office, a polarized cutoff relay at the central office, said relay being unresponsive to current flowing therethrough in one direction but responsive to current in the opposite direction adapted to render the calling-signal inoperative when connection is made with the line, a plurality of connectionterminals for said line, a cord-circuit consisting of two conductors and adapted to be placed in connection with the said connectionterminals, a source of current associated with said cord-circuit and adapted to send current over the line-circuit for energizing the sub scribers transmitter during conversation, a supervisory signal associated with said cordcircuit and adapted to be operated when connection is made with the line over a local circuit including the cut-off relay, and means controlled by the subscriber for rendering the said supervisory signal inoperative by current from the said source located in the cordcireuit and sent over the line, substantially as described.

34. In a telephone system, the combination with a subscribers instrument, of a line-circuit, a calling-signal and a polarized cut-off relay, said relay being adapted to render the calling-signal inoperative when a connection is made with the line, a connection-terminal for said line at the central office consisting of two contacts adapted to register with the two contacts of a cord-circuit, said cord-circuit including a source of current adapted to supply current for energizing the subscribers transmitter, a supervisory signal associated with the cord-circuit, said signal being operated when connection is made with the line and the subscribers instrument is not in' use by current flowing over one side of the talking-circuit and in a circuit local to the eX- change, said local circuit including an operative winding of the cut-off relay, means controlled by the removal of the subscribers instrument from its hook for rendering the supervisory signal inoperative by current sent over the main line from said source, and further means for maintaining the cut-off relay operated while connection is made with the line, substantially as described.

35. The combination with a in ultiple-switchboard common-battery telephone-line, of a battery connected between one line conductor and a third conductor, the other line eonductor being also connected with said third conductor, two or more busy-testing terminals connected with the latter line conductor, a polarized cut-off relay located in said latter conductor between the testing-terminals and the third conductor whereby said portion of the conductor possesses an appreciable resistance and when a subscriber calls and connects two conductors together the testing-terminals are raised to a potential above that of the third conductor and the line is in condition to test busy, and a cord-circuit having a busy-testing conductor connected to said third conductor to enable the operator to com plete a busy-testing circuit'and to receive a busy-test signal, substantially as described. 7

36. The combination with a multiple-switchboard common battery telephone -line, of a battery normally connected between one line conductor and a third conductor, the other line conductor being also connected with said third conductor, two or more busy-testing terminals connected with the latter line conductor, a polarized cut-off relay in a portion of said conductor between the testing-terminals and the third conductor whereby said conductor possesses an appreciable resistance and when a subscriber calls and connects two conductors together the testingterminals are raised to a potential above that of the third conductor, and an operators busytesting conductor also connected with said third conductor to enable her to complete the testing-circuit normally connected with the third conductor to enable the operator to complete a testing-circuit when the busy line is tested, substantially as described.

37. The combination with a multiple-switchboard common-battery telephone-line, of a battery connected between oneline conductor and the third conductor, the other line conductor being also connected with said third conductor, two or more busy-testi ng terminals permanently connected with the latter line conductor, a polarized cut-off relay located in the portion of said conductor between the testing-terminals and the third conductor, and having an appreciable resistance, and a cord-circuit having a busy-testing strand connected with said third conductor whereby when the subscriber calls his line is in condition to test busy and the operator is enabled to complete a testing-circuit to cause a testsignal, substantially as described.

38. In a telephone system, the combination with a telephone-line, of a common source of current with which the line is normally connected, a line-signal, a switch at the substation to normally control the flow of current in the line from said source to operate said signal, a polarized cut-oft device in the line in the path of calling-current but unresponsive to such current, a cord-circuit to establish conversational circuits with the line, a common source of current associated therewith and adapted to be included in the metallic line during connections to furnish current for talking, said latter source serving to reverse the direction of current through said out-off device to operate the same and render the line-signal inoperative, substantially as described.

39. In a telephone system, the combination with a telephone-line having a plurality of connection-terminals connected permanently therewith, of a line-signal therefor, a polarized cut-off device having its winding connected in the line, a switch at the substation to cause the flow of current in the line from ICO the central offioe to operate the line-signal, including part of the talking-circuit to operate said cut-off device being unresponsive to curthe same and thereby render the line-signal rent of that direction, a cord-circuit to estabinoperative, substantially as described.

lish connections with the line for conversa- In witness whereof I hereunto subscribe my 5 tion, a common source of current associated name in the presence of two witnesses.

therewith and adapted to be included in the metallic line to furnish current for talking, WILLIAM DEAN the current from said source during connec- Witnesses: tions being directed through said out-off de- E. F. BECK,

to vice in the opposite direction and over a path W. A. FRIGKE. 

